1212.2827 (Liang Du et al.)

Robust topological insulator surface conduction under strong surface
disorder    [PDF]

Liang Du, Quansheng Wu, Vincent E. Sacksteder IV

Topological insulators are characterized by specially protected conduction on their outer boundaries, i.e. on their surfaces. We show that the protected surface conduction exhibited by 2-D topological insulators is independent of non-magnetic surface disorder. In particular, the surface band remains conducting even when surface state inhomogeneities destroy the characteristic linear Dirac relation between energy and momentum. The main effects of disorder are to pull the surface states into the disordered layers, decrease their Fermi velocity, and increase the density of states. These effects are controlled by a resonance between the disorder potential and the bulk bands. The resonance's energy is set by the bulk band width; protection of the Dirac cone is controlled by the bulk band width, not the bulk band gap.

View original: http://arxiv.org/abs/1212.2827